Detachable Card Reader Secure PIN Entry on Mobile Devices

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Solution Overview

Problem

Conventional chip card readers are bulky and expensive, and mobile devices lack robust security measures to protect PIN entry during transactions.

Innovation Solution

A detachable card reader connects to a mobile device, allowing PIN entry on the device's touch display with security features like DRM-encoded interfaces and asymmetric encryption to prevent theft, and bi-directional communication through the audio jack for secure transactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional chip card readers are used, then transaction security is maintained, but device size and cost increase

Engineering Contradiction:
Improvetransaction securityVSAvoiddevice size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The card reading function is segmented from the mobile device and implemented as a separate detachable card reader accessory. This allows the mobile device to remain compact while the card reader provides dedicated secure card reading capabilities with proper shielding and antenna design for contactless transactions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A detachable card reader serves as an intermediary device between the card and the mobile device. It contains the necessary secure elements, shielding, and communication protocols to securely read card information and transmit it to the mobile device for processing, thereby maintaining security without requiring the mobile device itself to be bulky.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If conventional chip card readers are used, then transaction security is maintained, but device cost increases

Engineering Contradiction:
Improvetransaction securityVSAvoiddevice cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The detachable card reader is designed to work with multiple mobile devices and card types, amortizing its cost across many transactions and users. The same card reader can be used with different smartphones or tablets, reducing the per-unit cost compared to integrating dedicated card reading hardware into each mobile device.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The detachable card reader can be replaced or upgraded independently of the mobile device, allowing for cost-effective solutions where a simpler, less expensive card reader can be used with a high-end mobile device, or vice versa. This separates the investment between the durable mobile device and the potentially replaceable card reading accessory.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If PIN entry is performed on mobile device touch display, then ease of operation improves, but security against malware and unauthorized software deteriorates

Engineering Contradiction:
ImprovePIN entry convenienceVSAvoidPIN protection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system performs preliminary security checks and establishes encrypted communication channels before PIN entry begins. The mobile device and card reader authenticate each other and establish secure protocols in advance, preventing malware from intercepting or manipulating the PIN entry process.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The system provides feedback mechanisms to confirm secure communication status during PIN entry, such as visual indicators that encryption is active or that the card reader is authenticated. This allows the user to verify that their PIN entry is protected even though it occurs on the vulnerable touch display interface.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3907636B1Securely communicating between a card reader and a mobile device
Publication Date: 2025.12.10 BLOCK INC
  • EP3907636B1 patent drawingFigure 1
  • EP3907636B1 patent drawingFigure 2
  • EP3907636B1 patent drawingFigure 3

AI summary

A card reader configured to read a smart card can be detachably connected to a mobile computing device. When the card reader is attached to the mobile device, an application installed on the mobile computing device permits the mobile device to communicate with the card reader in order to process transactions. Security measures can be used on the mobile device to prevent theft of a PIN during software PIN entry of a payment transaction. The mobile device can prevent the keypad or other input interface from displaying feedback. The mobile device can also prevent passcodes from being stolen by displaying media encoded with digital rights management (DRM) and by managing the media and user inputs at a secure server. A mobile device can securely communicate with a card reader for a payment transaction using asymmetric or symmetric encryption.